lem #9: A mass attached to a spring, set in a container of molasses (a thick liquid) acts like a damped simple harmonic oscillator. The mass is 81 kg, the spring has a spring constant of 25 N/m and the molasses provides a damping force of 90 N-s/m. (a) The system is (A) underdamped (B) overdamped (C) critically damped (b) A force of F(t) = -3e >t/9 (in N) is applied to the mass. If the method of undetermined coefficients is used to find a particular solution, which of the following is the best choice as a trial solution? (c) Initially, at t = Os, our mass is moving at a speed of 8 m/s as it passes through its equilibrium position (x = 0m). If we are still under the force from part (b), at what positive time, in seconds, does it again pass through x = 0m? (If it never does, type dne). Problem #9(a): Select v (A) Ate St/9 (B) (At + B)e 5t/9 (C) A sinh(5t/9) + B cosh(5t/9) (D) At sinh(5t/9) + Bt cosh(5t/9) (E) (AP + Bt + C)e-5t/9 (F) (AP + Bi)e-51/9 (G) Ae-51/9 (H) ARe St/9 Problem #9(b): Select v 1 Part (b) choices. Enter your answer symbolically, Problem #9(c): as in these examples